RELATIONSHIPS BETWEEN SPINOCERVICAL TRACT NEURONS AND DESCENDING CATECHOLAMINE-CONTAINING AXONS IN THE CAT

Lumbosacral (L6-S1) spinal cord neurons in the cat were retrogradely l abelled after uptake of horseradish peroxidase by their severed axons in the upper cervical (C3-C4) dorsolateral funiculus. Sections of L6-S 1 containing labelled neurons were then processed immunocytochemically using antibodies against dopamine-beta-hydroxylase or tyrosine hydrox ylase, two enzymes responsible for the synthesis of catecholamines. Tw o hundred and ninety eight retrogradely-labelled cells within laminae III-V of the dorsal horn were examined under high power (x 1000) with the light microscope. In Triton X-100-treated material, only 13% of th ese cells had catecholamine-containing varicosities closely apposed to their somata and proximal dendrites, which suggests that in compariso n with the postsynaptic dorsal column pathway, spinocervical tract neu rons are only sparsely innervated by descending catecholaminergic axon s.